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PubMed1995

Distribution of catecholamines, indoleamines, and their precursors and metabolites in the scallop, Placopecten magellanicus (Bivalvia, Pectinidae).

1. Although monoamines are well-known to play important roles in molluscan physiology, we are far from fully understanding the synthetic and degradative pathways of these substances, particularly in commercially important bivalve species. In the present study endogenous catecholamines, indoleamines, and their possible precursors and metabolites were detected in the scallop, Placopecten magellanicus, by high-performance liquid chromatography coupled to electro-chemical detection. 2. Chromatographic analysis of CNS (cerebral, pedal, and parietovisceral combined), gill, gonad, kidney, mantle, liver, heart, fast adductor muscle, and foot disclosed the presence of the catecholamines 3,4-dihydroxyphenylalanine, dopamine, norepinephrine, and epinephrine and their metabolites normetanephrine, metanephrine, 3,4-dihydroxyphenylacetic acid, and homovanillic acid. 3. Dopamine was detected most frequently and most consistently among all catecholamines. The concentrations of dopamine (1400 pg/mg wet weight) and its major metabolite 3,4-dihydroxyphenylacetic acid (300 pg/mg wet weight) were highest in the CNS. Following the CNS, dopamine was also abundant in other tissues such as heart, foot, and gill. The concentration of norepinephrine (1000 pg/mg wet weight) was highest in the CNS followed by the heart (700 pg/mg wet weight) and gill (600 pg/mg wet weight). 4. The indoleamine, 5-hydroxytryptamine, was present in considerable amounts in all tissues, but its content was highest in the foot (2700 pg/mg wet weight) followed by the CNS (1150 pg/mg wet weight) and gonad (1000 pg/mg wet weight). The precursor 5-hydroxytryptophan was also abundant in the foot followed by the gonad, CNS, and heart. 5. The oxidative metabolite 5-hydroxy-3-indole acetic acid was detected in the largest amount in CNS (200 pg/mg wet weight), whereas N-acetyl-5-hydroxytryptamine was detected in trace amounts in CNS, gonad and foot. This study also presents evidence for gamma-glutamyl dopamine and gamma-glutamyl 5-hydroxytryptamine as the possible alternate catabolic products of dopamine and 5-hydroxytryptamine, respectively, as previously described in gastropods. 6. Thus, the detection of monoamines and their precursors and metabolites in scallop strongly suggests the presence of mammalian-type enzymic action of hydroxylation, oxidation, and methylation pathways leading to synthesis and degradation of detected compounds. Furthermore, this is the first study to disclose the evidence of nonconventional metabolic pathways for dopamine (gamma-glutamyl<--dopamine-->dihydroxyphenylacetic acid-->homovanillic acid) and 5-hydroxytryptamine (gamma-glutamyl 5-hydroxytryptamine<--5- hydroxytryptamine-->5-hydroxy-3-indoleacetic acid) inactivation in a bivalve species.

Animals↗
PubMed1969

Independence of Lateral and Differential Longitudinal Movement of Indoleactic Acid in Geotropically Stimulated Coleoptiles of Zea mays.

The possible interdependence of the differential longitudinal, and the lateral movement of indoleacetic acid (IAA) in horizontal Zea coleoptile segments has been examined. The coleoptiles have been opened out into flat pieces of tissue and supplied apically with IAA-1-(14)C.Opened-out segments orientated so that all the cells correspond with those at the ;bottom' of a normal horizontal coleoptile, transport more IAA basipetally than do segments in which all the cells are equivalent to those at the ;top' of the horizontal coleoptile.In opened-out segments orientated so that all the cells are equivalent to those at the side of the horizontal coleoptile cylinder, there is no difference in the basipetal transport capacity of the upper and lower halves. This is so even if the tissue has been in the horizontal position for 90 min before being bisected into its upper and lower halves. In this ;side' tissue, however, there is a polarized downward movement of IAA. At least 95% of the (14)C in both the upper and lower halves of the tissue is confined to the IAA molecule.In horizontal Zea coleoptiles the polarized lateral movement of IAA can therefore occur independently of the differential basipetal transport of IAA in the upper and lower halves of the organ.

Journal Article↗
PubMed1969

A Quantitative Estimation of Alkali-labile Indole-3-Acetic Acid Compounds in Dormant and Germinating Maize Kernels.

An estimate has been made of the quantities of alkali-labile esters of indoleacetic acid (IAA) in kernels of sweet corn (Zea mays). The amount is between 70 to 90 mg of IAA per kilogram of dry kernels. About one-half of the IAA is present as high molecular weight esters and the remaining one-half as esters of myo-inositol. Free IAA, which may have existed in the kernels, or may have resulted from ester hydrolysis during isolation or storage, amounts to between 1 to 10% of the esterified IAA. Five newly observed low molecular weight indoleacetyl compounds are described and their chromatographic behavior reported. The total IAA content of corn kernels and intact seedlings decreases during germination, declining to about 10% of the original content during 96 hr of germination. Difficulties in obtaining quantitative results and the possible physiological significance of these results is discussed.

Journal Article↗
PubMed1999

Histological changes and neurotransmitter levels three months following perinatal asphyxia in the rat.

The involvement of excitatory amino acids (EAA) in the pathogenesis of hypoxic-ischemic states is well-documented. Information on the role of overexcitation by EAA in perinatalasphyxia (PA), however, is limited and data from adult models cannot be directly extrapolated to immature systems. Moreover, most adult models of ischemia are representing stroke rather than PA. We decided to study long term effects in a non-invasive rat model of PA resembling the clinical situation three months following the asphyctic insult. Morphometry on Nissl - stained sections was used to determine neuronal death in frontal cortex, striatum, hippocampus CA1, hypothalamus and cerebellum L1, and the amino acids glutamate, glutamine, aspartate, GABA, taurine, arginine as well as histamine, serotonin and 5-hydroxy-indoleacetic acid were determined in several brain regions and areas. Morphometry revealed that neuronal loss was present in the hippocampal area CA1 in all groups with PA and that morphological alterations were significantly higher in the cerebellar granular layer. The prominent light microscopical finding in all areas of asphyctic rats studied was decreased Nissl-staining, suggesting decreased cellular RNA levels. Glutamate, aspartate and glutamine were significantly elevated in the hypothalamus of asphyctic rats probably indicating overstimulation by EAA. Excitotoxicity in this area would be compatible with findings of emotional / behavioral deficits observed in a parallel study in our model of PA. Our observations point to and may help to explain behavioral and emotional deficits in Man with a history of perinatal asphyxia.

Animals↗
PubMed1974

Pitfalls in using sodium hypochlorite as a seed disinfectant in C incorporation studies.

Seeds sterilized with sodium hypochlorite (NaOCl) retained sufficient amounts to interfere with studies of amino acid metabolism of the sterilized seeds during germination. Repeated washing in water did not remove NaOCl completely. However, soaking the seeds for 10 min in 0.01 n HCl removed NaOCl completely, without reducing germinability.Residual NaOCl reacted with the amino acids and reduced their concentrations in the incubation media. This reaction resulted in high production of CO(2) and low uptake of amino acids by the seeds. Decarboxylation of the amino acids occurred in the incubation medium outside the seed, was independent of the presence of seeds in the reaction, and therefore was not related to amino acid metabolism by the seeds. Effects of NaOCl on uptake, incorporation, and CO(2) production from indoleacetic acid were similar to those of the amino acids studied.

Journal Article↗
PubMed1989

Role of Ethylene in the Geotropic Response of Bermudagrass (Cynodon dactylon L. Pers.) Stolons.

We studied the relationship between ethylene and gravity-induced upward bending of bermudagrass (Cynodon dactylon L. Pers.) stolons. Ethylene production begins within 3 hours of the onset of gravistimulation, and increases thereafter until the 15th hour, after which it declines. There is a close positive relationship between ethylene production and upward bending during the first 12 hours of gravistimulation. Incubation of stolons with AgNO(3) did not prevent ethylene evolution but delayed upward bending. In addition, ethylene production was 10-fold greater and peaked earlier in gravistimulated nodes incubated with 1-aminocyclopropane 1-carboxylic acid. The gravitational stimulation could be due to an increase in both 1-aminocyclopropane 1-carboxylic acid synthase and the ethylene forming enzyme. The results suggest that ethylene promotes the activity of indoleacetic acid.

Journal Article↗
PubMed1970

Ribonucleic Acid Synthesis by Cucumber Chromatin: Developmental and Hormone-induced Changes.

When intact etiolated 2-day cucumber (Cucumis sativus) embryos were treated with indoleacetic acid (IAA), gibberellin A(7) (GA(7)), or kinetin, chromatin derived from the embryonic axes exhibited an increased capacity to support RNA synthesis in either the presence or the absence of bacterial RNA polymerase. An IAA effect on cucumber RNA polymerase activity was evident after 4 hours of hormone treatment; the IAA effect on DNA template activity (bacterial RNA polymerase added) occurred after longer treatments (12 hours). GA(7) also promoted template activity, but again only after a prior stimulation of endogenous chromatin activity. After 12 hours of kinetin treatment, both endogenous chromatin and DNA template activities were substantially above control values, but longer kinetin treatments caused these activities to decline in magnitude. When chromatin was prepared from hypocotyl segments that were floated on a GA(7) solution, a GA-induced increase in endogenous chromatin activity occurred, but only if cotyledon tissue was left attached to the segments during the period of hormone treatment.Age of the seedling tissue had a profound influence on the chromatin characteristics. With progression of development from the 2-day to the 4-day stage, the endogenous chromatin activity declined while the DNA template activity increased.

Journal Article↗
PubMed1987

Decreased plasma serotonin in melancholic patients: a study with clomipramine.

Eighteen unmedicated patients suffering from major depressive disorder with melancholia (DSM-III) were examined for abnormalities in peripheral serotonin (5-HT) and related metabolites. Serotonin in platelet-free plasma and in platelets from melancholics was significantly reduced to 30% and 60% of their respective control values. Plasma 5-hydroxyindoleacetic acid was also found to be reduced, but not significantly. Other plasma compounds related to 5-HT (indoleacetic acid, total tryptophan, and free tryptophan) were found to be unchanged in these patients. Of all variables, only platelet 5-HT was affected while patients were on clomipramine (CIM) treatment. After 2 weeks on CIM (100-150 mg/day, orally), platelet 5-HT was reduced to 8% of pretreatment values, but plasma 5-HT did not change and continued to be reduced upon clinical recovery. The existence of a distinct pool of plasma 5-HT that is clearly independent of the platelet pool is indicated by the differences observed in plasma and platelet 5-HT during CIM treatment, as well as by previous data from this laboratory. The very marked decrease in plasma 5-HT levels may be in accord with the central nervous system changes reported in depression and suggests the possibility of using plasma 5-HT as a peripheral indicator of abnormal serotonin function in melancholia.

Aged↗
PubMed1983

Effect of Lithium on Thigmomorphogenesis in Bryonia dioica Ethylene Production and Sensitivity.

Rubbing internodes of Bryonia dioica plants reduced their ethylene production but increased their capacity to convert 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. These results were explained by the previously shown rubbing-induced decrease of indoleacetic acid, which controls the level of ACC synthase, and by the increase of membrane-associated peroxidases which would participate in the conversion of ACC-ethylene. Pretreatment of the plants with Li had no significant effect on control plants but counteracted the rubbing-induced decrease of ethylene production and diminished the capacity of the internodes to convert ACC to ethylene. Exogenously applied ethylene induced an increase of peroxidase activity similar to that caused by rubbing. Inasmuch as both effects were reduced by Li, it was concluded that Li inhibition of thigmomorphogenetic processes was essentially due to a Li inhibition of the effect of ethylene formed in response to mechanical stimuli. The decreased ethylene production and ACC conversion capacity in the presence of Li were explained by a cellular redistribution of peroxidases.

Journal Article↗
PubMed1970

Factors involved in the opening of the hypocotyl hook of cotton and beans.

Conditions influencing the opening of the bean (Phaseolus vulgaris L.) and cotton (Gossypium hirsutum L.) hypocotyl hook were defined. Such hooks were shown to undergo geotropic curvature; orientation of the hook with respect to gravity greatly affected the observed opening. Cotton and bean hooks behaved exactly opposite in regard to the presence of the cotyledons and apical bud. The cotton hook required the cotyledons for opening, but the corresponding tissue slowed or inhibited opening of the bean hook. With cotton, lower hypocotyl and root tissues stimulated hook opening, but with bean, the tissues below the hook section had little effect. Kinetin and gibberellic acid both modified hook opening in light and dark; the former was inhibitory and the latter was stimulatory. Indoleacetic acid, at concentrations above 10(-5) M, caused pronounced hook closing in red light but not in the dark. These effects were generally the same with both plants. In opening of the cotton hook, the cotyledons were not necessary as a light receptor tissue. None of the growth substances tested were able to substitute completely for the cotton cotyledon. Coumarin was a pronounced inhibitor of opening of the cotton hook, and this response was expressed to such a degree as to cause hook closure with bean tissue. Reduced oxygen levels inhibited hook opening in bean. Oxygen was required in processes subsequent to the light reaction, but not for the photochemical process.

Journal Article↗
PubMed1974

Effect of red light on coleoptile growth.

The effects of red light in reducing the growth of the oat (Avena sativa L.) coleoptile and the synthesis of auxin in the coleoptile tip are detectable 2 hours after treatment and become more pronounced with time. When the coleoptile tip is supplied with additional tryptophan the synthesis of auxin is doubled both in darkness and when exposed to red light. Treatment of the tip with gibberellic acid or pyridoxal phosphate overcomes the reduction of auxin synthesis caused by red light. The uptake of exogenous indoleacetic acid, at pH 6.5, by coleoptile tissue is doubled by exposure to red light. The effect of red light on coleoptile growth appears to be mediated by phytochrome in the cell membrane which delocalizes the tryptophan utilized for auxin synthesis.

Journal Article↗
PubMed1983

Ethylene production by auxin-deprived, suspension-cultured pear fruit cells in response to auxins, stress, or precursor.

Auxin-deprived, mannitol-supplemented, suspension-cultured pear (Pyrus communis L. Passe Crassane) fruit cells produce large quantities (20-40 nanoliters ethylene per 10(6) cells per hour) of ethylene in response to auxins, CuCl(2) or 1-amino-cyclopropane-1-carboxylic acid (ACC). Maximum rates of production are achieved about 12 hours after the addition of optimal amounts of indoleacetic acid (IAA), naphthalene acetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), 4 to 5 hours after the addition of CuCl(2) and 1 to 2 hours after the addition of ACC. Supraoptimal concentrations of IAA result in a lag phase followed by a normal response. High concentrations of NAA and 2,4-D result in an early (4-5 hours) stress response and injury.Continuous protein and RNA synthesis are essential for elaboration of the full IAA response; only protein synthesis is necessary for the response to CuCl(2) and ACC. Based on polysomal states and rates of amino acid incorporation, CuCl(2) partially inhibits protein synthesis while nonetheless stimulating ethylene production. In general, ethylene production by the pear cells resembles that of other plant systems. Some differences may reflect the sensitivity of the cells and are discussed. The relatively high levels of ethylene produced and the experimental convenience of the cultured cells should make them especially suitable for further investigations of ethylene production and physiology.

Journal Article↗
PubMed1973

Rapid growth inhibition of Avena coleoptile segments by abscisic Acid.

An angular position sensing transducer was used to make continuous measurements of elongation of a column of Avena sativa coleoptile segments. Elongation stimulated by 2 mum indoleacetic acid was inhibited by 0.1 mm abscisic acid with a latent period of about 4 or 5 minutes at pH 6.0, 30 C. Full growth inhibition was not established until about 1 hour after the addition of the abscisic acid. The same degree of final growth inhibition could be obtained under the above conditions using 10 muM and 1 muM abscisic acid, but the latent period was longer. Pretreatments with abscisic acid affected the growth rate but did not extend the latent period of a subsequent response to auxin. The short term kinetics of inhibition by abscisic acid were not similar to those of any of the inhibitors of RNA and protein synthesis tested in this system.

Journal Article↗
PubMed1999

Neurotransmitter levels in two populations of larval Fundulus heteroclitus after methylmercury exposure.

The effects of methylmercury (MeHg) exposure on neurotransmitter (NT) levels in larval mummichogs (Fundulus heteroclitus) obtained from a mercury-polluted site (Piles Creek (PC), NJ) and a reference site (Tuckerton (TK), NJ) were examined. Population differences between PC and TK larvae in neurochemical composition and in neurochemical changes in response to MeHg intoxication were found. Heads of untreated PC larvae (7 days posthatch (dph)) contained considerably higher levels of dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) than TK. However, they had comparable levels of serotonin (5-hydroxytryptamine (5-HT)) and 5-hyroxy-3-indoleacetic acid (5-HIAA)/5-HT ratios. Changes in NTs with age were noticed, especially in PC larvae. Exposure of larvae to 10 microg/l MeHg induced neurochemical alterations. A significant increase in DA and 5-HT, as well as depressed dopaminergic and serotonergic activity (i.e. decreased DOPAC/DA, HVA/DA and 5-HIAA/5-HT ratios) were seen in TK larvae. Exposure of PC larvae to 10 microg/l MeHg reduced 5-HT at 14 dph, increased serotonergic activity at 7 dph, and altered dopaminergic activity (i.e. increased DOPAC/DA ratios, but decreased HVA/DA ratios). Changes in DA levels were inconsistent over time. The DA level, which was considerably higher than the control at 7 dph, was significantly lower than the control at 14 dph. For the two populations, the level of 5-HT and serotonergic activity, as well as DOPAC and HVA levels, were correlated with previously noted spontaneous activity. The changes in NT levels after exposure to MeHg are an indication of neurological dysfunction in larvae.

Animals↗
PubMed1979

Role of auxin and gibberellin in differentiation of primary Phloem fibers.

The hypothesis that auxin and gibberellic acid (GA(3)) control the differentiation of primary phloem fibers is confirmed for the stem of Coleus blumei Benth. Indoleacetic acid (IAA) alone sufficed to cause the differentiation of a few primary phloem fibers. In long term experiments auxin induced a considerable number of fibers in mature internodes. GA(3) by itself did not exert any effect on fiber differentiation. Combinatiosn of IAA with GA(3) completely replaced the role of the leaves in primary phloem fiber differentiation qualitatively and quantitatively. Although the combined effect of the two growth hormones diminished considerably with increasing distance from the source of induction, auxin with GA(3) or IAA alone induced fibers in a few internodes below the application site. When various combinations of both hormones were applied, high concentrations of IAA stimulated rapid differentiation of fibers with thick secondary walls, while high levels of GA(3) resulted in long fibers with thin walls. The size of the primary phloem fibers correlated with the dimensions of the differentiating internode, thereby providing evidence that both growth regulators figure in the control of stem extension. High IAA/low GA(3) concentrations have an inhibitory effect on internode elongation, whereas low IAA/high GA(3) concentrations promote maximal stem elongation.

Journal Article↗
PubMed1991

The 1-aminocyclopropane-1-carboxylate synthase of Cucurbita. Purification, properties, expression in Escherichia coli, and primary structure determination by DNA sequence analysis.

The key regulatory enzyme in the biosynthetic pathway of the plant hormone ethylene is 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (EC 4.4.1.14). We have partially purified ACC synthase 6,000-fold from Cucurbita fruit tissue treated with indoleacetic acid + benzyladenine + aminooxyacetic acid + LiCl. The enzyme has a specific activity of 35,000 nmol/h/mg protein, a pH optimum of 9.5, an isoelectric point of 5.0, a Km of 17 microM with respect to S-adenosylmethionine, and is a dimer of two identical subunits of approximately 46,000 Da each. The subunit exists in vivo as a 55,000-Da species similar in size to the primary in vitro translation product. DNA sequence analysis of the cDNA clone pACC1 revealed that the coding region of the ACC synthase mRNA spans 493 amino acids corresponding to a 55,779-Da polypeptide; and expression of the coding sequence (pACC1) in Escherichia coli as a COOH terminus hybrid of beta-galactosidase or as a nonhybrid polypeptide catalyzed the conversion of S-adenosylmethionine to ACC (Sato, T., and Theologis, A. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 6621-6625). Immunoblotting experiments herein show that the molecular mass of the beta-galactosidase hybrid polypeptide is 170,000 Da, and the size of the largest nonhybrid polypeptide is 53,000 Da. The data suggest that the enzyme is post-translationally processed during protein purification.

Amino Acid Sequence↗
PubMed1969

Blockage by gibberellic Acid of phytochrome effects on growth, auxin responses, and flavonoid synthesis in etiolated pea internodes.

Red light inhibits the growth of etiolated pea internodes, causes a shift toward higher indoleacetic acid (IAA) concentrations in the IAA dose-response curve of excised sections, and promotes the synthesis in intact internodes of kaempferol-3-triglucoside. Gibberellic acid (GA(3)) prevents all 3 effects, the first effect substantially and the last 2 completely. This suggests GA(3) blockage of an early or basic event initiated by the active form of phytochrome. The red light-induced shift in the IAA dose-response curve of excised sections is consistent with a light-induced increase in the activity of an IAA destruction system, since the magnitude of the red light inhibition varied with IAA concentration. The red light and GA(3) effects on growth and on flavonoid synthesis are consistent with the view that phytochrome may control growth by regulating the synthesis of phenolic compounds which act as cofactors in an IAA-oxidase system. GA(3) reversal of the red light-induced shift in the IAA dose-response curve involves both growth promotion and inhibition by GA(3) at different IAA concentrations and this, together with the GA(3) reversal of light-induced flavonoid synthesis, supports the suggested regulatory role of phenolic compounds in growth.

Journal Article↗
PubMed1994

N-methyl-D-aspartate receptors modulate extracellular 5-hydroxytryptamine concentration in rat hippocampus and striatum in vivo.

The effects of infusing N-methyl-D-aspartate (NMDA) and the specific NMDA receptor antagonist D-2-amino-5-phosphonopropionic acid (D-AP5) into rat hippocampus and striatum on extracellular 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxy-indoleacetic acid (5-HIAA) were studied using intracerebral microdialysis. In striatum, NMDA (1-100 microM) caused a concentration-dependent increase in 5-HT. D-AP5 (10 microM) infusion caused increased extracellular 5-HT. When the two drugs were co-infused, no effect on extracellular 5-HT was seen. D-AP5 alone was found to cause a delayed but sustained increase in dialysate 5-HIAA. In hippocampus, NMDA infusion caused a dose-dependent decrease in extracellular 5-HT while D-AP5 produced a transitory increase in 5-HT level. NMDA caused a decrease in dialysate 5-HIAA. In striatum, the effect of 10 microM NMDA infusion was abolished by co-infusion with tetrodotoxin (TTX; 1 microM). In hippocampus, 1 microM TTX caused a slight but non-significant augmentation of the effect of 10 microM NMDA alone. These data indicate that NMDA receptors mediate control over 5-HT release and metabolism in different brain regions and may in part explain the behavioural effects of non-competitive NMDA receptor antagonists.

2-Amino-5-phosphonovalerate↗